A Research Note on Mixed Organochlorine Pesticide Degradation: DDT and Endosulphan in Compost‐Amended Aerobic and Cyclic Treatments

Persistent organochlorine pesticides (OCPs), notably dichlorodiphenyltrichloroethane (DDT) and endosulfan, continue to pose significant environmental challenges decades after their ban, particularly in rural and legacy agrochemical sites. This rapid assessment pilot study evaluated the efficacy of low‐cost, biologically based remediation strategies for OCP‐contaminated soils at a former agrochemical facility in regional New South Wales, Australia. Five treatment configurations were tested over a 12‐week period, varying in compost amendment and aeration regimes, including cyclic aeration with and without compost, aerobic composting, passive aerobic treatment, and an abiotic control. Results indicated that non‐composted treatments with cyclic or passive aeration achieved the most substantial reductions in DDT concentrations, with decreases of up to 67%. Compost‐amended treatments exhibited enhanced microbial activity but did not correspond to greater contaminant degradation within the trial duration. Importantly, the study also documented co‐occurring endosulfan, which showed partial reduction in several treatments despite low initial concentrations, highlighting the potential of simple, scalable bioremediation systems to address mixed OCP contamination. Limitations such as small‐scale pile sizes, composite sampling, and short treatment duration may have influenced the outcomes. The findings suggest that simple, scalable bioremediation approaches can be effective for managing complex OCP‐contaminated soils in resource‐limited settings. Future research should focus on longer‐term trials, stratified sampling, and detailed microbial and metabolite analyses to optimize strategies for dual‐contaminant remediation.